1. Field of the Invention
This invention relates to a position detection system for detecting the position of a mobile body in the space in which of the mobile body is moved.
2. Description of the Related Art
Systems of arranging a rotary-type laser radar on a mobile body to know the position of the mobile body, anchoring at least three reflectors in a space surrounding the mobile body and scanning the surroundings of the mobile body by means of a laser beam emitted from the laser radar are known (see, for example, Jpn. Pat. Appln. Publication No. 2003-302469).
With such a system, it is possible to detect the presence or absence of light reflected from each of the reflectors as a result of scanning with a laser beam and also the direction of each of the reflectors as viewed from the mobile body according to the information on the scanning angle of the laser beam. Additionally, it is possible to detect the distance between the mobile body and each of the reflectors by gauging the time spent for the laser beam to be reflected by the reflector and returning to the laser radar. Then, it is possible to detect the position of the mobile body according to the detected direction and the detected distance.
However, with the above-described system, after anchoring the reflectors in a space surrounding the mobile body, it is necessary to emit a laser beam, placing the mobile body at a fixed point, and carry out various operations of calibration/registration relative to the mobile body for initialization according to light reflected from each of the reflectors. The initialization is a cumbersome operation for the operator. The cumbersomeness is multiplied when there is a plurality of mobile bodies because it is necessary to carry out the operations of initialization for each mobile body.
Additionally, the above-described system is accompanied by a problem that the mobile body becomes large, can malfunction and involves large cost because a rotary-type laser radar needs to be arranged on the mobile body.